1. Field of the invention
The present invention concerns a thermal protection device designed to protect the cylindrical casing of a ramjet engine combustion chamber.
The invention is more particularly concerned with an internal thermal protection device for hollow structures subjected to the ablative flow of corrosive gases at high speeds and high temperatures and to high-level vibrations, in particular where such phenomena are inherent to their operation, and with a method of manufacturing this device.
2. Description of the Prior art
In the current state of the art the thermal protection layers of such structures are made from composite materials using organic, organo-metallic or mineral binders possibly including powder, fiber, mineral or organic woven reinforcement. When exposed to hot gases the ablatable material is pyrolyzed. This pyrolysis is accompanied by deterioration of the carbon-based or organo-silicic chain of the binder which renders the scoria fragile and breakable within the mass of material. To alleviate this the thermal protection layer is usually reinforced, by various techniques.
It is known that the ablation of a material of this kind subjected to erosion by hot gases and to vibration is reduced when the material is reinforced. The reinforcing armature embedded in the insulating material may be metallic or non-metallic, woven or fibrous.
The patent U.S. Pat. No. 4,655,866 describes a reinforced thermal protection device of this kind and the method of manufacturing it. The device is for thermally protecting walls along which gas flows, such as ramjet engine combustion chambers.
This prior art patent is of interest because it enabled the development of a flexible, for example silicone protection, reinforced in particular by an armature oriented relative to the gas flow, which confers good resistance to ablation and to loss of material due to vibration inherent to operation of the engine.
An object of the invention is to improve the performance of a device as disclosed in the aforementioned patent, in particular with regard to its mechanical strength following pyrolysis of the binder.